Program and control device

ABSTRACT

A program and a control device capable of calibrating a detection value of a sensor that detects contact with a steering wheel are provided. The program in accordance with the present invention is characterized by causing a computer to execute processing of distinguishing whether or not a user is on a driver&#39;s seat of a vehicle; acquiring, from a sensor ( 21 ) that converts contact with a steering wheel ( 2 ) into an electric signal for detection, a detection value of the detected electric signal; determining whether or not a difference between the detection value acquired when it has been distinguished that the user is not on the driver&#39;s seat, and a reference value is equal to or larger than a threshold value; and setting the detection value as the reference value when it has been determined that the difference is not equal to or larger than the threshold value.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a 35 U.S.C. § 371 national phase application of PCT International Application No. PCT/JP2016/083452, filed Nov. 11, 2016, which claims the benefit of priority under 35 U.S.C. § 119 to Japanese Patent Application No. JP2015-223324, filed Nov. 13, 2015, the contents of which are incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

The present invention relates to a computer program stored on a non-transitory memory device and which is executed by a computer processor and other hardware components to carry out the processing of signals and providing certain control functions, and a control device for a motor vehicle application.

BACKGROUND

Technologies for supporting and assisting driving of a vehicle such as so-called lane keeping assistance, parking assistance, or automated driving has been developed. These systems are generally known as advanced driver assistance systems or “ADAS”. Herein, for the determination of the propriety of intervention of driving support during vehicle driving, a technology of allowing intervention of driving support when a steering wheel is in a grasped state has been proposed.

Japanese Patent Application Publication No. 2015-131544 discloses a vehicle control device capable of switching between execution and cancellation of driving support. According to the above-cited reference, an electrostatic sensor provided in the steering wheel of a vehicle detects the magnitude of the electrostatic capacitance associated with contact with or approach to the steering wheel, by the hands of the driver, and switches between validity and invalidity of driving support according to the detection value of the detected electrostatic capacitance.

On the other hand, the state of the sensor provided in a vehicle may be changed according to, for example, secular deterioration or environmental variation. Accordingly, even when the steering wheel is in a non-grasped state, the detection value of the sensor may indicate a value corresponding to a grasped state. In the above-cited reference, the solution to the change in state of the sensor is not disclosed.

The present invention was completed under such circumstances. It is an object thereof to provide a program executed by appropriate hardware components and a control device capable of calibrating the detection value of the sensor for detecting the contact with a steering wheel.

SUMMARY

The present invention is related to a computer program stored on a non-transitory memory device and which is executed by a computer processor and other hardware components to carry out the processing of signals and providing certain control functions. In accordance with the present invention a computer is enabled while operating through hardware components to execute processing of: distinguishing whether or not a user is occupying a driver's seat of a vehicle; acquiring, from a sensor that converts contact with a steering wheel into an electric signal for detection, a detection value of a detected electric signal; determining whether or not a difference between the detection value acquired when it has been distinguished that the user is not on the driver's seat, and a reference value is equal to or larger than a threshold value; and setting the detection value as the reference value when it has been determined that the difference is not equal to or larger than the threshold value.

An embodiment of the present invention is further characterized in that the sensor is a capacitive sensor that detects an electrostatic capacitance to be coupled to an electrode provided at the steering wheel, and is characterized by causing execution of processing of acquiring a detection value of the electrostatic capacitance detected by the capacitive sensor.

An embodiment of the present invention is further characterized by causing execution of processing of: distinguishing whether or not a user is on the driver's seat by distinguishing an opening operation or unlocking of a door of the vehicle; distinguishing whether or not an in-vehicle device mounted in the vehicle is in a second mode in which a power consumption of the in-vehicle device is lower than that of a first mode in which the in-vehicle device is being operated; starting acquisition of the detection value when the opening operation or unlocking of the door has been distinguished, and when the in-vehicle device has been distinguished as being in the second mode; and determining whether or not a difference between a detection value acquired at the time of starting acquisition of the detection value, and the reference value is equal to or larger than a threshold value.

An embodiment of the present invention is further characterized by causing execution of processing of distinguishing an opening operation or unlocking of a door related to the driver's seat.

An embodiment of the present invention is further characterized by causing execution of processing of distinguishing unlocking of the door when a detection result indicative of detection of a transportable radio communication device situated within a prescribed distance from the vehicle has been acquired.

An embodiment of the present invention is further characterized by causing execution of processing of: outputting a notification signal giving notification about an abnormality in the sensor when the difference has been determined as being equal to or larger than a threshold value.

An embodiment of the present invention is further characterized by causing execution of processing of: continuously outputting the notification signal; newly acquiring the detection value from the sensor after start of outputting of the notification signal; determining whether or not a difference between the detection value and the reference value is equal to or larger than a threshold value; and stopping outputting of the notification signal when the difference has been determined as not being equal to or larger than the threshold value.

A control device in accordance with the present invention is characterized by including: a distinguishing part that distinguishes whether or not a user is on a driver's seat of a vehicle; an acquisition part that acquires, from a sensor that converts contact with a steering wheel into an electric signal for detection, a detection value of the detected electric signal; a determination part for determining whether or not a difference between the detection value acquired when it has been distinguished that the user is not on the driver's seat, and a reference value is equal to or larger than a threshold value; and a setting part that sets the detection value as the reference value when it has been determined that the difference is not equal to or larger than the threshold value.

In accordance with the present invention, the detection value of a sensor for detecting the contact with a steering wheel can be calibrated.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a configuration example of a grasp determination system.

FIG. 2 is an explanatory view showing one example of a steering wheel having an electrode.

FIG. 3 is an explanatory view showing the state in which the door of the driver's seat is opened for climbing into a vehicle.

FIG. 4 is a flowchart showing one example of the procedure of the grasp determination.

FIG. 5 is a block diagram showing a configuration example of a grasp determination system in accordance with a second embodiment.

FIG. 6 is a flowchart showing one example of the procedure of the grasp determination system in accordance with a second embodiment.

FIG. 7 is a flowchart showing one example of the procedure of a grasp determination system in accordance with the third embodiment.

DETAILED DESCRIPTION

Below, the present invention will be described in details based on the drawings showing the embodiments.

FIG. 1 is a block view showing a first embodiment of a configuration example of a grasp determination system. The grasp determination system is provided in a vehicle, includes a capacitive sensor 21 for converting the contact with a steering wheel 2 into an electric signal for detection, and detects grasping of a steering wheel 2 by a user. Further, in the present embodiment, the grasp determination system diagnoses the state of the capacitive sensor 21 for detecting the contact with the steering wheel 2, and performs processing of calibrating the detection value of the capacitive sensor 21.

The grasp determination system includes in-vehicle devices such as a grasp determination ECU (Electronic Control Unit) 1, the steering wheel 2, a door ECU 3, an engine ECU 4, a notification device 5, a driving support ECU 6, and an opening/closing sensor 7. Each in-vehicle device is communication connected by an in-vehicle network provided in a vehicle.

The steering wheel 2 includes, for example, the capacitive sensor 21 for detecting the electrostatic capacitance to be coupled with an electrode provided in the inside thereof. The capacitive sensor 21 includes, for example, a sensor circuit, and a C/V (capacitance to voltage) conversion circuit, and detects the electrostatic capacitance to be coupled to the electrode.

The grasp determination ECU 1 acquires the detection value of the electrostatic capacitance detected by the capacitive sensor 21, and determines whether or not the steering wheel 2 is in a grasped state. Further, the grasp determination ECU 1 determines whether or not the state of the capacitive sensor 21 is abnormal based on the detection value.

The grasp determination ECU 1 includes, for example, a control part 11, a storage part 12, a communication part 13, and a capacitance measurement circuit 14.

The control part 11 includes an arithmetic processing device such as a CPU (Central Processing Unit) or a MPU (Micro-Processing Unit). The control part 11 performs various kinds of information processing, control processing, or the like in accordance with the grasp determination ECU 1. Further, the control part 11 executes determination processing described later based on the electrostatic capacitance detected at the capacitive sensor 21.

The storage part 12 includes memory elements such as a RAM (Random Access Memory) and a ROM (Read Only Memory), and stores a program P, data, or the like necessary for the control part 11 to execute processing. Further, the storage part 12 temporarily stores data or the like necessary for the control part 11 to execute processing. Furthermore, the storage part 12 stores the reference value of the electrostatic capacitance necessary for determination processing described later. Still further, the storage part 12 stores a specified value of the electrostatic capacitance previously set.

The communication part 13 is a communication interface for performing transmission/reception of information via an in-vehicle network. The communication part 13 is connected to a communication line provided in a vehicle, and performs transmission/reception of information with the door ECU 3, the engine ECU 4, the notification device 5, or the like.

The capacitance measurement circuit 14 is an electric circuit for measuring the detection value of the electrostatic capacitance. The capacitance measurement circuit 14 processes the electric signal acquired from the capacitive sensor 21, and calculates the detection value of the electrostatic capacitance. The calculated detection value of the electrostatic capacitance is given to the control part 11.

Incidentally, in the present embodiment, the electric signal detected by the capacitive sensor 21 is processed at the grasp determination ECU 1, to calculate the detection value of the electrostatic capacitance. However, the present embodiment is not limited thereto. For example, the following configuration is also acceptable: the capacitance measurement circuit 14 is provided in the inside of the steering wheel 2, and the detection value of the electrostatic capacitance is transmitted to the grasp determination ECU 1.

The door ECU 3 is an ECU for controlling the opening/closing of a vehicle door, and the like. The door ECU 3 is connected to, for example, the opening/closing sensor 7 for detecting the opening/closing of the door, and notifies the grasp determination ECU 1, and the like of the detection result by the opening/closing sensor 7.

The door ECU 3 includes, for example, a control part 31 and a communication part 32. The control part 31 includes, for example, a CPU and a MPU, and performs control processing, information processing, and the like in accordance with the door ECU 3. The communication part 32 is a communication interface for performing transmission and reception of information via an in-vehicle network, and performs transmission and reception of information with the grasp determination ECU 1.

The engine ECU 4 detects ON or OFF of an ignition switch (not shown) provided at the driver's seat of a vehicle, and starts or stops the engine of the vehicle based on the detection result. Further, the engine ECU 4 notifies the grasp determination ECU 1, and the like of the ON or OFF state of the ignition switch.

The notification device 5 is a device for notifying a user of the abnormality of the capacitive sensor 21 based on the notification signal transmitted from the grasp determination ECU 1. For example, the notification device 5 is a speaker, and outputs a prescribed warning sound, and thereby performs notification to a user. Incidentally, it is essential only that the notification device 5 may perform notification to a user, and may be, for example, a display device or an indicator.

The driving support ECU 6 receives a signal indicating the grasped state or the non-grasped state of the steering wheel 2 from the grasp determination ECU 1, and executes processing in accordance with prescribed driving support. For example, the driving support ECU 6 is an ECU for executing processing in accordance with automated driving, and executes automated driving when the steering wheel 2 is in a non-grasped state, and executes manual driving when the steering wheel 2 is in a non-grasped state. Incidentally, the processing contents of driving support in accordance with the present embodiment is not limited to automated driving, and may be, for example, lane keeping assistance or parking assistance.

FIG. 2 is an explanatory view showing one example of the steering wheel 2 having an electrode 2 a. Referring to FIGS. 1 and 2, the outline of the grasp determination system will be described. Incidentally, below, for convenience of description, the processing main part of the grasp determination ECU 1 is assumed to be the control part 11, and the processing main part of the door ECU 3 is assumed to be the control part 31.

As shown in FIG. 2, for example, the steering wheel 2 has a plurality of electrodes 2 a in the inside thereof. The electrodes 2 a are conductive members, and, for example, three electrodes 2 a are provided along the circumference of the steering wheel 2 in such a form as to divide the circumference into three parts. Incidentally, the number of the electrodes 2 a is not limited to 3, and may be either 2 or less, or 4 or more. Further, the configurations of the shape, materials, arrangement, and the like of the electrode 2 a have no particular restriction, and various design changes can be considered.

The electrode 2 a is connected to, for example, a C/V conversion circuit (not shown) in accordance with the capacitive sensor 21. The C/V conversion circuit applies, for example, the electrode 2 a with an alternating voltage with a prescribed amplitude, and outputs an alternating voltage in accordance with the magnitude of the electrostatic capacitance to be coupled with the electrode 2 a. The sensor circuit (not shown) in accordance with the capacitive sensor 21 detects the outputted voltage, and thereby detects the electrostatic capacitance coupled with the electrode 2 a.

When the steering wheel 2 is in a non-grasped state, the electrode 2 a is electrically capacitive-coupled with GND (ground) of the vehicle body or the like via the air in the vehicle compartment. When the steering wheel 2 is in a grasped state, in other words, when the user's hand is in contact with the steering wheel 2, approach to the hand of the user causes the electrode 2 a to be capacitive-coupled with the human body of the user. When the electrode 2 a is capacitive-coupled with the GND, the capacitive coupling is the capacitive coupling with the ground plane. Accordingly, the electrostatic capacitance becomes very small. In contrast, the human body has a given electric conductivity. For this reason, the electrostatic capacitance resulting from coupling between the human body of the user and the electrode 2 a becomes larger than the electrostatic capacitance resulting from coupling between the GND and the electrode 2 a. The grasp determination system in accordance with the present embodiment determines the grasped state or the non-grasped state of the steering wheel 2 based on the difference in the electrostatic capacitance.

Referring back to FIG. 1, the control part 11 of the grasp determination ECU 1 processes an electric signal indicating the electrostatic capacitance detected by the capacitive sensor 21 in the capacitance measurement circuit 14, and acquires the detection value of the electrostatic capacitance. The control part 11 determines whether or not the steering wheel 2 is in a grasped state based on the difference between the detection value and the reference value. Specifically, the control part 11 performs determination by whether or not the difference between the detection value and the reference value is equal to or larger than a prescribed threshold value. The prescribed threshold value corresponds to the difference between respective electrostatic capacitances in the case of being in a grasped state or in a non-grasped state, and is set at, for example, 100 pF. Incidentally, the threshold value is not limited to the value. The reference value is the value changed by setting processing described later.

The grasp determination ECU 1 determines the grasped state or the non-grasped state of the steering wheel 2, and transmits a signal indicating the determination result to the driving support ECU 6, and the like. For example, the driving support ECU 6 executes processing in accordance with driving support based on the received determination result.

FIG. 3 is an explanatory view showing the state in which the door of the driver's seat is opened for climbing into the vehicle. Incidentally, FIG. 3 does not show the engine ECU 4, the notification device 5, and the like. Below, a description will be given to setting processing of setting the reference value of the electrostatic capacitance and notification processing of notifying a user of the abnormality of the capacitive sensor 21.

As described above, the grasp determination system determines the grasped state or the non-grasped state by the electrostatic capacitance detected by the capacitive sensor 21 provided at the steering wheel 2. However, the detection value may be changed according to degradation over time of the capacitive sensor 21, environmental changes, short circuit of the electrode 2 a, and the like. When the detection value of the electrostatic capacitance is changed, for example, the detection value increases even in a non-grasped state, resulting in an increase in difference between the detection value and the reference value. As a result, the control part 11 may erroneously determine the non-grasped state as the grasped state.

The grasp determination system in accordance with the present embodiment performs setting processing of the reference value and notification processing of the abnormality of the capacitive sensor 21 in order to cope with the foregoing situation.

A consideration will be given to, for example, the case where the engine of a vehicle is stopped with a user not being on the driver's seat. In this case, the control part 11 of the grasp determination ECU 1 puts the own device (grasp determination ECU 1) into the suspended mode for power saving. The suspended mode is the mode with a lower power consumption of the in-vehicle devices such as the grasp determination ECU 1, the engine ECU 4, and the driving support ECU 6 mounted in the vehicle than that of the operating mode in which the in-vehicle devices operate. For example, when the control part 11 receives a signal indicative of turning off of the ignition switch from the engine ECU 4, the control part 11 puts the own device into the suspended mode after a prescribed time from the reception of the signal. Incidentally, in order to keep the operating mode until a user gets out of the vehicle, the control part 11 puts the own device into a suspended mode after a prescribed time from reception of the signal. The control part 11 suppresses the power consumption of the own device low during the suspended mode, and detects whether a signal has been received or not at, for example, the communication part 13 so as to enable reception of a signal transmitted from the door ECU 3 or the like.

Incidentally, in the present embodiment, the control part 11 performs switching between the operating mode or the suspended mode by ON or OFF of the ignition switch. However, the present embodiment is not limited thereto. For example, the control part 11 may perform switching between the operating mode or the suspended mode based on the communication state in the in-vehicle network. In this case, for example, the control part 11 puts the own device into the suspended mode after a prescribed time from interruption of communication at the communication part 13.

It is assumed that when the grasp determination ECU 1 was in the suspended mode, a user opened the door of the driver's seat. When the control part 31 of the door ECU 3 detects the opening operation of the door, the control part 31 of the door ECU 3 transmits a signal indicating the detection result to the grasp determination ECU 1. The control part 11 of the grasp determination ECU 1 determines whether the door was opened or not based on whether the signal was received or not. Incidentally, the following is also acceptable: the control part 31 of the door ECU 3 continuously or periodically transmits a signal regarding opening/closing of the door to the grasp determination ECU 1; and the control part 11 of the grasp determination ECU 1 determines whether the door was opened or not based on the received signal.

When the control part 11 determines that the door of the driver's seat was opened, the control part 11 starts the own device, and changes the own device from the suspended mode into the operating mode. The control part 11 which has started the own device starts processing of acquiring the detection value of the electrostatic capacitance to be coupled to the electrode 2 a detected by the capacitive sensor 21.

For example, when the grasp determination ECU 1 is in the suspended mode due to stopping of the engine and the door of the driver's seat is opened, it can be considered that the user opened the door of the driver's seat to be on the driver's seat as shown in FIG. 3. Therefore, it is estimated that the user is not on the driver's seat, and that the steering wheel 2 is in the non-grasped state. Thus, the control part 11 performs setting processing of the reference value and notification processing of the abnormality of the capacitive sensor 21 based on the initial value of the electrostatic capacitance at the time of starting acquisition of the detection value estimated as being in the non-grasped state.

The control part 11 determines whether or not the difference between the initial value and the reference value of the electrostatic capacitance is equal to or larger than a prescribed threshold value. The prescribed threshold value corresponds to, for example, the difference between respective electrostatic capacitances in the cases of the grasped state and the non-grasped state as above, and is set at 100 pF. The reference value is the value stored at the storage part 12, and the value set by the control part 11 by the previous setting processing.

When the control part 11 determines that the difference between the initial value and the reference value of the electrostatic capacitance is not equal to or larger than the threshold value, the control part 11 performs setting processing of the reference value. Specifically, the control part 11 sets the initial value acquired at the time of start of acquiring the detection value as a new reference value. As described above, the capacitive sensor 21 may show varying detection value of the electrostatic capacitance due to the secular change, or the like. Thus, in the present embodiment, in order to set the reference value based on the changes in state of the capacitive sensor 21, the initial value of the electrostatic capacitance acquired at the time of start of acquiring the detection value is set as the reference value.

The control part 11 performs grasp determination processing based on the reference value in the subsequent grasp determination processing in accordance with automated driving. The processing has already been described in details, and hence a description thereon is herein omitted.

The control part 11 stores, for example, the newly set reference value at the storage part 12. When detection processing of the electrostatic capacitance is started next time, the control part 11 reads the reference value stored at the storage part 12, and performs setting processing of the reference value or notification processing of the abnormality of the capacitive sensor 21.

When the difference between the initial value and the reference value of the electrostatic capacitance is determined to be equal to or larger than the threshold value, the control part 11 performs notification processing of notifying a user of the abnormality of the capacitive sensor 21 because the detection value of the electrostatic capacitance is large regardless of being in the state estimated as the non-grasped state. For example, the control part 11 generates a prescribed notification signal, and transmits the signal to the notification device 5. When the notification device 5 receives the notification signal, the notification device 5 outputs, for example, a prescribed warning sound, and thereby notifies a user of the abnormality of the capacitive sensor 21.

It is assumed that when the grasp determination ECU 1 was in the operating mode, a user opened the door. In this case, for example, the case where a user opened the door for getting out from the vehicle is also conceivable. Accordingly, it cannot be estimated that a user is not on the driver's seat. For this reason, the control part 11 does not perform the setting processing or the notification processing. Instead, the control part 11 performs processing of setting the previously set specified value as the reference value. The specified value is the value of electrostatic capacitance previously stored at the storage part 12, and is, for example, 0 pF. The control part 11 performs subsequent grasp determination processing in accordance with automated driving based on the reference value (specified value).

Incidentally, in the present embodiment, it was assumed that when the control part 11 distinguished the opening operation of the door during the operating mode of the own device, the control part 11 sets the reference value of electrostatic capacitance as the specified value. However, the present embodiment is not limited thereto. In this case, the following is also acceptable: the control part 11 does not change the reference value, and performs grasp determination processing based on the reference value set in the previous setting processing.

FIG. 4 is a flowchart showing one example of the procedure of the grasp determination system. Referring to FIG. 4, a description will be given to the processing operation of the grasp determination system.

The control part 11 of the grasp determination ECU 1 determines whether the door related to the driver's seat was opened or not (Step S11). For example, the control part 11 performs determination based on whether or not a prescribed signal indicating the detection result indicative of opening of the door was received from the door ECU 3. When the control part 11 determines that the door is not opened (Step S11: NO), the control part 11 waits processing. When the control part 11 determined that the door was opened (Step S11: YES), the control part 11 determines whether the own device is in the suspended mode or not (Step S12).

When the control part 11 determines that the own device is in the suspended mode (Step S12: YES), the control part 11 starts the own device, and puts the own device into the operating mode (Step S13). The control part 11 starts processing of acquiring the detection value of the electrostatic capacitance detected by the capacitive sensor 21 (Step S14). Specifically, the capacitive sensor 21 detects the electrostatic capacitance to be coupled to the electrode 2 a provided at the steering wheel 2, and transmits an electric signal indicating the detected magnitude of the electrostatic capacitance to the grasp determination ECU 1. The control part 11 of the grasp determination ECU 1 processes the received electric signal at the measurement circuit 15, and starts processing of acquiring the detection value of the electrostatic capacitance. The control part 11 determines whether or not the difference between the initial value of the electrostatic capacitance at the time of start of acquiring the detection value and the reference value is equal to or larger than a prescribed threshold value (Step S15). The reference value is the reference value of the electrostatic capacitance set at previous or earlier processing, and is stored at, for example, the storage part 12.

When the control part 11 determines that the difference between the initial value and the reference value is equal to or larger than the threshold value (Step S15: YES), the control part 11 transmits a notification signal notifying of the abnormality of the capacitive sensor 21 to the notification device 5 (Step S16). As a result, the notification device 5 performs notification to a user. The control part 11 terminates a series of processing.

When the control part 11 determines that the difference between the initial value and the reference value is not equal to or larger than the threshold value (Step S15: NO), the control part 11 sets the initial value as the reference value (Step S17). When the control part 11 performs grasp determination of the steering wheel 2 in accordance with automated driving, the control part 11 performs grasp determination based on the reference value (initial value) set at Step S17. The control part 11 terminates a series of processing.

When the control part 11 determines that the own device is not in the suspended mode (Step S12: NO), the control part 11 sets a previously set specified value as the reference value (Step S18). For example, the specified value is the value previously stored at the storage part 12, and 0 pF. When the control part 11 performs grasp determination of the steering wheel 2 in accordance with driving support, the control part 11 performs grasp determination based on the reference value (specified value) set at Step S18. Incidentally, the processing of Step S18 can be omitted. When the control part 11 determines that the own device is not in the suspended mode, the control part 11 is not required to change the reference value. The control part 11 terminates a series of processing.

Incidentally, in the flowchart shown in FIG. 4, for convenience of description, a description has been given assuming that, after performing the determination processing for whether or not the door was opened (Step S11), the determination processing for whether or not the own device is in the suspended mode (Step S12) is performed. However, the present embodiment is not limited thereto. In other words, by inverting the procedure of Step S11 and Step S12, the control part 11 may determine whether the door was opened or not when the control part 11 determined that the own device was in the suspended mode.

Incidentally, in the present embodiment, the control part 11 of the grasp determination ECU 1 distinguishes whether or not a user is on the driver's seat by distinguishing the opening operation of the door. However, the present embodiment is not limited thereto. For example, the following is also acceptable: a camera for imaging the driver's seat is provided in a vehicle; and the control part 11 distinguishes whether or not a user is on the driver's seat based on the image imaged by the camera.

Further, in the present embodiment, the sensor for detecting contact with the steering wheel 2 is the capacitive sensor 21. However, the present embodiment is not limited thereto. For example, the sensor may be a resistive sensor including a piezoelectric element or an induction sensor including a coil. Alternatively, the sensor may be a sensor obtained by combining detection elements such as a resistance, a capacitor, and a coil. In other words, it is essential only that the sensor can convert the contact with the steering wheel 2 into an electric signal for detection.

From the description up to this point, in accordance with the present Embodiment 1, the grasp determination ECU 1 acquires, from the sensor for converting the contact with the steering wheel 2 into an electric signal for detection, the detection value of the electric signal. Then, when the grasp determination ECU 1 determines that the difference between the detection value and the reference value is not equal to or larger than the threshold value with a user not being on the driver's seat, the grasp determination ECU 1 sets the detection value as the reference value. When a user is not on the driver's seat, the steering wheel 2 can be estimated to be in the non-grasped state. Accordingly, the detection value of the sensor for detecting the contact with the steering wheel 2 can be calibrated.

Further, in accordance with the present Embodiment 1, the capacitive sensor 21 is provided at the steering wheel 2. The grasp determination ECU 1 acquires the detection value of the electrostatic capacitance detected by the capacitive sensor 21. As a result, the grasp determination ECU 1 can determine the contact with the steering wheel 2 by the detection value of the electrostatic capacitance.

Further, in accordance with the present Embodiment 1, the grasp determination ECU 1 distinguishes the opening operation of the door in the suspended mode of the own device, and thereby distinguishes whether or not a user is on the driver's seat. As a result, the grasp determination ECU 1 can estimate the non-grasped state of the steering wheel 2. Further, when the grasp determination ECU 1 distinguishes that a user is not on the driver's seat, the grasp determination ECU 1 starts to acquire the detection value, and determines whether or not the difference between the initial value acquired at the time of starting the acquisition and the reference value is equal to or larger than the threshold value. As a result, the grasp determination ECU 1 can perform determination processing based on the detection value (initial value) in the non-grasped state.

Further, in accordance with the present Embodiment 1, the grasp determination ECU 1 distinguishes the opening operation of the door related to the driver's seat. As a result, the grasp determination ECU 1 can distinguish whether or not a user is on the driver's seat.

Further, in accordance with the present Embodiment 1, when the grasp determination ECU 1 determines that the difference between the initial value and the reference value of the electrostatic capacitance is equal to or larger than the threshold value, the grasp determination ECU 1 outputs a notification signal notifying of the abnormality of the sensor to the notification device 5. As a result, the grasp determination ECU 1 can notify a user of the abnormality of the sensor.

In the first embodiment, a description has been given to the aspect in which the grasp determination ECU 1 distinguishes the opening operation of the door of the driver's seat, and thereby distinguishes whether or not a user is on the driver's seat. In the present embodiment, further, a description will be given to the following aspect: the grasp determination ECU 1 distinguishes unlocking of the door of the driver's seat, and thereby distinguishes whether or not a user is on the driver's seat. Incidentally, the descriptions overlapping those in Embodiment 1 are given the same signs and numerals, and will not be described.

FIG. 5 is a block view showing a configuration example of a grasp determination system in accordance with a second embodiment of the invention. As shown in FIG. 5, the grasp determination system in accordance with the present embodiment includes a radio key ECU 203 and a radio key 208 other than the grasp determination ECU 1, the door ECU 3, and the like. The radio key ECU 203 is an ECU having a radio communication module, and the like for performing radio communication with the outside. Further, the radio key ECU 203 is connected to the communication line provided in a vehicle, and performs transmission and reception of information with the grasp determination ECU 1, and the like. The radio key 208 is a transportable radio communication device carried by a user, a portable device related to so-called keyless entry.

As shown in FIG. 5, the radio key ECU 203 includes, for example, a control part 231, a storage part 232, a communication part 233, and a radio communication part 234. The control part 231 includes, for example, a CPU, a MPU, and the like, and performs various types of control processing, information processing, and the like in accordance with the radio key ECU 203. The storage part 232 includes a ROM, a RAM, and the like, and stores various data and the like necessary for the control part 231 to perform processing, and stores an identifier for identifying the radio key 208. The communication part 233 is a communication interface for performing transmission and reception of information via an in-vehicle network. The radio communication part 234 is a radio communication module including, for example, an antenna and a communication processing circuit, and performs radio communication with the outside.

Incidentally, the radio key ECU 203 may be not configured to perform radio communication by the radio communication part 234 provided at the own device, but may be configured to be connected to a radio communication device provided in the vehicle via an in-vehicle network, and to perform radio communication by the radio communication device. Further, in the present embodiment, the radio key ECU 203 and the door ECU 3 are configured as different control devices. However, the radio key ECU 203 and the door ECU 3 may be configured as an integrated control device.

The radio key 208 includes, for example, a control part 281, a storage part 282, and a radio communication part 283. The control part 281 includes, for example, a CPU and a MPU, and performs various types of control processing and information processing in accordance with the radio key 208. The storage part 282 includes a ROM, a RAM, and the like, and stores various data and the like necessary for the control part 281 to perform processing, and stores an identifier in accordance with the radio key 208. The radio communication part 283 is a radio communication module including, for example, an antenna and a communication processing circuit, and performs radio communication with the outside.

Incidentally, for example, the radio key 208 may be configured to include an operation part for receiving the operation input by a user, and to transmit a radio signal based on the operation input to the operation part.

Referring to FIG. 5, a description will be given to the outline of the processing operation of the grasp determination system in accordance with the present embodiment. Incidentally, for convenience of description, the processing main part of the radio key ECU 203 is assumed to be the control part 231, and the processing main part of the radio key 208 is assumed to the control part 281.

The control part 231 of the radio key ECU 203 intermittently transmits, for example, to the outside. The radio signal is a beacon notifying of the location of the own device, and is set so as to be transmitted within a prescribed distance from the vehicle.

When the control part 281 of the radio key 208 receives the radio signal, the control part 281 generates a radio signal including an identifier of the radio key 208, and transmits the radio signal to the radio key ECU 203.

The control part 231 of the radio key ECU 203 receives a radio signal from the radio key 208. The control part 231 reads the identifier included in the radio signal, and determines whether or not the identifier is in agreement with the identifier stored at the storage part 232. When the control part 231 determines the agreement between the identifiers, the control part 231 determines that the radio key 208 of the own vehicle was detected within a prescribed distance from the vehicle, and transmits, for example, a prescribed signal indicating unlocking of the door to the door ECU 3. As a result, the door ECU 3 unlocks the door of the vehicle.

Further, when the control part 231 determines the agreement between the identifiers, for example, the control part 231 transmits a prescribed signal indicating the detection result to the grasp determination ECU 1. When the control part 11 of the grasp determination ECU 1 receives the signal during the suspended mode of the own device, the control part 11 of the grasp determination ECU 1 determines that a user is not on the driver's seat. The control part 11 starts the own device, and starts processing of acquiring the detection value of the electrostatic capacitance from the capacitive sensor 21.

FIG. 6 is a flowchart showing one example of the procedure of the grasp determination system in accordance with the second embodiment. Referring to FIG. 6, a description will be given to the processing operation of the grasp determination system in accordance with the present embodiment. Incidentally, the disruptions overlapping those in Embodiment 1 are given the same signs and numerals, and will not be described.

The control part 11 of the grasp determination ECU 1 determines whether or not unlocking of the door related to the driver's seat of a vehicle was performed (Step S201). Specifically, the control part 231 of the radio key ECU 203 accepts reception of the radio signal transmitted from the radio key 208. When the radio signal from the radio key 208 is received, the control part 231 transmits a signal indicating the detection result indicative of detection of the transportable radio key 208 situated within a prescribed distance from the vehicle to the grasp determination ECU 1. The control part 11 of the grasp determination ECU 1 performs determination by whether or not the signal was received.

When the control part 11 determines that unlocking of the door of the driver's seat was not performed (Step S201: NO), the control part 11 determines whether or not the door related to the driver's seat of the vehicle was opened (Step S202). For example, the control part 11 performs determination based on whether or not the signal indicating the detection result indicative of detection of the opening operation of the door from the door ECU 3. When the control part 11 determines that the door of the driver's seat is not opened (Step S202: NO), the control part 11 returns the processing to Step S201.

When the control part 11 determines that the door of the driver's seat was unlocked (Step S201: YES), or when the control part 11 determines that the door of the driver's seat was opened (Step S202: YES), the control part 11 transfers the processing to Step S12.

Incidentally, in the present embodiment, a description has been given to the configuration in which unlocking or locking of the door is performed by so-called keyless entry. However, a configuration in which unlocking or locking of the door is performed by a mechanical key is also acceptable. In this case, for example, the door ECU 3 is connected to a door locking sensor for detecting the operation of the door locking mechanism related to the door of the driver's seat. The door ECU 3 detects unlocking of the door of the driver's seat by the door locking sensor, and transmits the detection result to the grasp determination ECU 1.

From the description up to this point, in accordance with the present second embodiment, the grasp determination ECU 1 can distinguish whether or not a user is on the driver's seat also by the unlocking operation of the door of the driver's seat.

Further, in accordance with the present second embodiment, the grasp determination ECU 1 can distinguish whether or not a user is on the driver's seat also by the unlocking operation in accordance with so-called keyless entry.

In the first embodiment, a description has been given to the following aspect: when the difference between the initial value of the electrostatic capacitance detected by the capacitive sensor 21 and the reference value is equal to or larger than the threshold value, the grasp determination ECU 1 controls the notification device 5, and notifies a user of the abnormality of the capacitive sensor 21. In the third embodiment, a description will be given to the following aspect: the grasp determination ECU 1 continuously performs notification processing of the abnormality of the capacitive sensor 21, and, when the detection value of the capacitive sensor 21 returns to the normal value, the grasp determination ECU 1 stops the notification processing. Incidentally, the descriptions overlapping those in Embodiment 1 are given the same reference numerals and signs, and will not be described.

In the third embodiment, when the control part 11 of the grasp determination ECU 1 determines that the difference between the initial value and the reference value of the electrostatic capacitance is equal to or larger than the threshold value, the control part 11 continuously performs notification processing of notifying a user of the abnormality of the capacitive sensor 21. Specifically, when the control part 11 determines that the difference between the initial value and the reference value of the electrostatic capacitance is equal to or larger than the threshold value, the control part 11 starts transmission of a notification signal to the notification device 5, and continuously performs the transmission processing. As a result, the notification device 5 continuously performs notification to a user.

The control part 11 determines whether or not the detection value by the capacitive sensor 21 returned to the normal value after starting transmission of the notification signal. When the control part 11 determines that the detection value returned to the normal value, the control part 11 performs processing of stopping transmission of the notification signal. Specifically, the control part 11 continues to perform detection processing of the electrostatic capacitance by the capacitive sensor 21 also after starting notification processing of the abnormality of the capacitive sensor 21. Further, the control part 11 continues to perform processing of determining whether or not the difference between the detection value acquired by the detection processing and the reference value is equal to or larger than the threshold value. Incidentally, the detection processing may also be performed periodically.

In the case where the difference between the detection value and the reference value of the electrostatic capacitance is less than the threshold value, for example, it can be considered as follows: when a user temporarily moves his or her hands off the steering wheel 2, the detection value by the capacitive sensor 21 does not show an abnormal value, but returns to the normal value. Thus, in the present embodiment, when the control part 11 determines that the difference between the detection value and the reference value of the electrostatic capacitance is not equal to or larger than the threshold value in the determination processing, the control part 11 stops transmission of the notification signal to the notification device 5.

FIG. 7 is a flowchart showing one example of the procedure of a grasp determination system in accordance with Embodiment 3. Referring to FIG. 7, a description will be given to the processing operation of the grasp determination system in accordance with the present embodiment. Incidentally, the descriptions overlapping those in Embodiment 1 are given the same reference numerals and signs, and will not be described.

When the difference between the initial value and the reference value is determined to be equal to or larger than the threshold value (Step S15: YES), the grasp determination system in accordance with the present embodiment executes the following processing. The control part 11 starts processing of transmitting a notification signal notifying of the abnormality of the capacitive sensor 21 to the notification device 5 (Step S301). As a result, the notification device 5 continuously performs notification to a user. The control part 11 newly acquires a detection value of the electrostatic capacitance, and determines whether or not the difference between the detection value and the reference value is equal to or larger than the threshold value (Step S302). When the control part 11 determines that the difference between the detection value and the reference value is equal to or larger than the threshold value (Step S302: YES), the control part 11 waits processing.

When the control part 11 determines that the difference between the detection value and the reference value is not equal to or larger than the threshold value (Step S302: NO), the control part 11 stops transmission processing of the notification signal to the notification device 5 (Step S303). As a result, the notification device 5 stops processing of notifying a user of the abnormality of the capacitive sensor 21. The control part 11 terminates a series of processing.

Incidentally, in the present embodiment, when the control part 11 of the grasp determination ECU 1 determines that the difference between the detection value and the reference value of the electrostatic capacitance is not equal to or larger than the threshold value, the control part 11 only stops notification processing. However, the present embodiment is not limited thereto. The following is also acceptable: the control part 11 stops notification processing, and sets the detection value of the electrostatic capacitance when the difference is determined not to be equal to or larger than the threshold value as the reference value. As a result, the control part 11 can set the detection value determined as the normal value as another reference value.

From the description up to this point, in accordance with the present third embodiment, the grasp determination ECU 1 continues determination processing of comparing the detection value and the reference value of the electrostatic capacitance also after notification of the abnormality of the capacitive sensor 21, and stops notification processing upon determining that the detection value returned to the normal value. As a result, for example, when the detection value of the electrostatic capacitance temporarily shows an abnormal value, the grasp determination ECU 1 can perform proper processing.

It should be understood that the embodiments disclosed this time are examples in all respects, and not limitative. The scope of the present invention is defined not by the foregoing meaning, but by the scope of the appended claims, and all changes that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

While the above description constitutes the preferred embodiment of the present invention, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope and fair meaning of the accompanying claims. 

The invention claimed is:
 1. A system for calibrating a sensor within a vehicle, comprising: a processor; and a non-transitory memory device storing a computer program that causes the processor to: distinguish whether or not an in-vehicle device mounted in the vehicle is in a second mode corresponding to an ignition switch of the vehicle being off; distinguish whether or not a user is on a driver's seat of the vehicle by distinguishing an opening operation or unlocking of a door of the vehicle; acquire, from a sensor that converts contact with a steering wheel into an electric signal for detection, a detection value of a detected electric signal; determine whether or not a difference between the detection value acquired when it has been distinguished that the user is not on the driver's seat and when the in-vehicle device has been distinguished as being in the second mode, and a reference value is equal to or larger than a threshold value; and set the reference value to be equal to the detection value when it has been determined that the difference is not equal to or larger than the threshold value.
 2. The system according to claim 1, wherein the sensor is a capacitive sensor that detects an electrostatic capacitance to be coupled to an electrode provided at the steering wheel, and the electric signal is the detection value of the electrostatic capacitance detected by the capacitive sensor.
 3. The system according to claim 1, wherein the computer program further causes the processor to: start acquisition of the detection value when the opening operation or unlocking of the door has been distinguished, and when the in-vehicle device has been distinguished as being in the second mode; and determine whether or not the difference between the detection value, acquired at a time of starting acquisition of the detection value, and the reference value is equal to or larger than the threshold value.
 4. The system according to claim 3, wherein the door of the vehicle is a door related to the driver's seat.
 5. The system according to claim 3, causing execution of processing of: distinguishing unlocking of the door when a detection result indicative of detection of a transportable radio communication device situated within a prescribed distance from the vehicle has been acquired.
 6. The system according to claim 1, further comprising, causing execution of processing of: outputting a notification signal giving notification about an abnormality in the sensor when the difference has been determined as being equal to or larger than the threshold value.
 7. The system according to claim 6, further comprising, causing execution of processing of: continuously outputting the notification signal; newly acquiring the detection value from the sensor after a start of outputting of the notification signal; determining whether or not a new difference between the detection value and the reference value is equal to or larger than the threshold value; and stopping outputting of the notification signal when the new difference has been determined as not being equal to or larger than the threshold value.
 8. A method for calibrating a sensor in a vehicle, comprising: distinguishing whether an in-vehicle device mounted in the vehicle is in a second mode corresponding to an ignition switch of the vehicle being off; distinguishing whether a user is on a driver's seat of a vehicle by distinguishing an opening operation or unlocking of a door of the vehicle; acquiring, from a sensor that converts contact with a steering wheel into an electric signal for detection, a detection value of a detected electric signal; determining whether a difference between the detection value acquired when it has been distinguished that the user is not on the driver's seat and when the in-vehicle device has been distinguished as being in the second mode, and a reference value is equal to or larger than a threshold value; and setting the reference value to be equal to the detection value when it has been determined that the difference is not equal to or larger than the threshold value.
 9. The method of claim 8, wherein the sensor is a capacitive sensor that detects an electrostatic capacitance to be coupled to an electrode provided at the steering wheel, and wherein acquiring the detection value of the detected electric signal includes acquiring a detection value of the electrostatic capacitance detected by the capacitive sensor.
 10. The method of claim 8, wherein acquiring the detection value is performed when the opening operation or unlocking of the door has been distinguished, and when the in-vehicle device has been distinguished as being in the second mode; and wherein determining whether the difference between the detection value and the reference value is equal to or larger than the threshold value is performed at a time of starting acquisition of the detection value.
 11. The method of claim 8, wherein the door of the vehicle is a door related to the driver's seat.
 12. The method of claim 8, wherein distinguishing an opening operation or unlocking of a door of the vehicle includes distinguishing unlocking of the door when acquiring a detection result indicative of detection of a transportable radio communication device situated within a prescribed distance from the vehicle.
 13. The method of claim 8, further comprising outputting a notification signal giving notification about an abnormality in the sensor when the difference has been determined as being equal to or larger than the threshold value.
 14. The method of claim 13, further comprising: newly acquiring the detection value from the sensor after a start of outputting of the notification signal; determining whether a new difference between the detection value and the reference value is equal to or larger than the threshold value; and stopping outputting of the notification signal when the new difference has been determined as not being equal to or larger than the threshold value. 